Solidified biomass and production method thereof

ABSTRACT

A solidified biomass consisting of semi-carbonized or pre-semi-carbonized solid matter is pressure-formed from raw biomass material while being heated and has a maximum compressive strength of 60-200 MPa and calorific value of 18-23 MJ/kg. A method for producing the solidified biomass: includes crushing raw biomass material; loading a barrel with the crushed raw biomass material; inserting a pressure applying piston into a hollow of the barrel; pressure-forming the crushed raw biomass materials by applying pressure with the pressure applying piston while heating the material; obtaining semi-carbonized or pre-semi-carbonized solid matter by retaining constant time of the heating and the pressurizing; cooling the semi-carbonized or pre-semi-carbonized solid matter while maintaining pressure to obtain a cooled solid; and taking out and drying the cooled solid, wherein the pressure applying piston and the hollow of the barrel have very small clearance between their outer and inner peripheries.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the right of priority as a continuation-in-partunder 35 U.S.C. §120, as authorized by 35 U.S.C. §365(c), toInternational Application No. PCT/JP2006/300985, filed on Jan. 24, 2006by the same inventors (published under PCT Article 21(2) in Japanese andnot English), which in turn claims priority from International PatentApplication No. PCT/JP2005/000880, filed on Jan. 24, 2005, by the sameinventors (published under PCT Article 21(2) in Japanese and notEnglish), each of which is incorporated herein by reference in itsentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to solidified biomass and a productionmethod thereof, and more specifically relates to solidified biomassutilizable as an alternative fuel to coal coke and also as materialutilizable for a variety of purposes and production methods thereof.

The raw biomass material according to the present invention is definedas a refreshable organic resource derived from organism other thanfossil fuel. In this specification, maximum compressive strength (MPa)is indicative of hardness based on JISZ2111 ‘Compression Test Method ofWood’

A technique for carbonizing the raw biomass material (completecarbonization) is as follows. The raw biomass material such as wood,bark, bamboo or rice hull is heated within the space in which oxygendoes not exist or is supplied under control, and then products areobtained, such as gas (e.g., wood gas), liquid (e.g., acetic acid, tar)or solid (e.g., charcoal). In particular, in this invention, thesemi-carbonized solid is obtained by stopping carbonizing the rawbiomass material before it is completely carbonized so that the rawbiomass material is carbonized without releasing combustible gas orliquid. Because the semi-carbonized solid and pre-semi-carbonized solidare in solid state, their transport efficiency and energy efficiency areincreased.

2. Description of the Related Art

Global environment problems has become more and more serious in recentyears, and reduction of greenhouse gas emission based on Kyoto Protocoladopted at the 3^(rd) conference of the parties of the United NationsFramework Convention on Climate Change (COP3), securement of primaryenergy sources, and development of clean and renewable energy sourceshave been pressingly needed in consideration of predicted depletion offossil fuel in the future.

Biomass has garnered attention as a breakthrough to overcome thesituation at the present days.

However, crude biomass material is high in void fraction, bulky, andvery low in transportation efficiency. Further, it is relatively low incalorific value, development of transformational technology to convertit to high-value-added products is demanded.

On the other hand, for rapid iron and steel demand in china in recentyears, the cost of the coal coke soars suddenly, and the management offoundry industry and iron and steel manufacturers in our country isremarkably oppressed. This is attributable to the fact that domesticproduction of coal coke is poor and manufacturers of our country dependmore on Chinese-produced coal coke.

In the face of such a circumstance, it is desired earnestly in the fieldof foundry and iron making to develop solid fuel of high hardness madeof biomass that can be substituted for several percentages to severaltens of percentages of coal coke, thereby reducing fuel cost and alsoreducing greenhouse gas emission by virtue of carbon-neutral nature ofthe biomass.

Further, it is important that the quality of ingot is not degraded inquality by utilizing alternative coke fuel.

As technology for utilizing heat of biomass, there are disclosed pelletprocessing technology (see patent literature 1 mentioned below, forexample) and ogalite processing technology (see patent literature 2mentioned below, for example) as well as widely known carbonization ofbiomass.

Pellets and ogalite are pressure-densified fuel made by dewatering byallowing free water contained in wood to evaporate at 100° C., therebyimproving transportability and combustibility.

Further, there are disclosed a processing method in which biomassmaterial is cut into narrow chips and carbonized in order to obtaincarbide efficiently (see patent literature 3 mentioned below, forexample), a processing method for producing solid fuel with high energyyield having high energy density by volume and weight (see patentliterature 4 mentioned below, for example), and a processing method forproducing half-carbonized and pressure-densified fuel (Bio-Carbonizedand Densified Fuel, hereafter referred to as BCDF) of hightransportability to further improve transportability (see patentliterature 5 mentioned below, for example).

BCDF is solid fuel from which a part of chemically-bonded watercontained in cellulose, etc. as well as free water contained in wood aredehydrated, thereby further improving transportability andcombustibility.

The patent literatures 1 to 5 aim to produce solid fuel with increasedheat energy yield in order to efficiently utilize woody biomass as aheat source.

However, woody biomass group solid fuel produced by methods mentionedabove does not have enough calorific value as compared with coal cokeand further is not enough in hardness. Therefore, the solid fuel cannotendure the severe condition when burned in the furnace together withcoal coke; it is destroyed and burned in the furnace, resulting in thatit is difficult for the solid fuel to work as alternative fuel to coalcoke.

Further, there are various kinds of biomass such as herb group biomass(grass, sunflower, etc.) and leftover food group biomass (bean-curdrefuse, rice hulls, etc.), which are higher in water content and higherin void fraction as compared with wood biomass, so less suitable toutilize as solid fuel, and have been disposed of unutilized. Means toeffectively utilize those kinds of biomass has been groped.

Patent literature 1: Japanese Laid-Open Patent Application No.S52-101202

Patent literature 2: Japanese Utility Model Gazette No. H08-8085

Patent literature 3: Japanese Laid-Open Patent Application No.2004-43517

Patent literature 4: Japanese Laid-Open Patent Application No.2003-213273

Patent literature 5: Japanese Laid-Open Patent Application No.2003-206490

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

The present invention was made in light of the problems mentioned above,and the object of the invention is to provide solidified biomassutilizable as alternative fuel to coal coke and also as materialutilizable for a variety of purposes and production methods thereof.

Means for Solving the Problem

One embodiment of the present invention provides a solidified biomassconsisting of semi-carbonized solid matter or pre-semi-carbonized solidmatter resulted through processing in which raw biomass material whichis photosynthetic product is pressure-formed while being heated under asubstantially sealed-up condition. The semi-carbonized solid is producedby carbonizing the raw biomass material without releasing combustiblegas or liquid, and the pre-semi-carbonized has the state before becomingthe state of the semi-carbonized solid. The pre-semi-carbonized orsemi-carbonized solid has maximum compressive strength from 60 to 200MPa and a calorific value from 18 to 23 MJ/kg.

In another embodiment of the present invention, the pre-semi-carbonizedor semi-carbonized solid matter has an apparent specific gravity from1.2 to 1.38.

In another embodiment of the present invention, the solidified biomassconsists of carbide formed by further pressure-forming thepre-semi-carbonized or semi-carbonized solid matter while heating thesame.

Another embodiment of the present invention provides solidified biomass,wherein the pre-semi-carbonized or semi-carbonized solid matter isformed by mixing raw biomass material which is photosynthetic productwith metal particles, and then pressure-forming the resultant mixturewhile heating it.

Another embodiment of the present invention provides a solidifiedbiomass consisting of the pre-semi-carbonized or semi-carbonized solidmatter formed by mixing raw biomass material which is photosyntheticproduct with particulate carbide having biomass as main components, andthen pressure-forming the resultant mixture while heating the same.

Another embodiment of the present invention provides a solidifiedbiomass consisting of the pre-semi-carbonized or semi-carbonized solidmatter formed by mixing raw biomass material which is photosyntheticproduct with ash of material having biomass as main component and beingreduced to the ash, and then pressure-forming the resultant mixturewhile heating the same.

Another embodiment of the present invention provides a method ofproducing solidified biomass comprising:

crushing raw biomass material which is photosynthetic product;

loading a barrel with said crushed raw biomass material;

inserting a pressure applying tool slidably into a hollow of said barrelloaded with said crushed raw biomass material so that pressure can beapplied to said crushed raw biomass material by said pressure applyingtool;

pressure-forming said crushed raw biomass materials by applying pressureto the material with said pressure applying tool slidably inserted intothe barrel while heating the material;

allowing hemicellulose among main component aid raw biomass material,i.e. lignin, cellulose and hemicellulose, to be thermally decomposed andallowing low-temperature reaction to occur between cellulose and ligninwhile maintaining their skeletons, thereby obtaining semi-carbonizedsolid mater or pre-semi-carbonized solid matter;

cooling said semi-carbonized solid mater or pre-semi-carbonized solidmatter while maintaining pressure of said pressure-forming to obtain acooled solid; and

taking out and drying said cooled solid.

In another embodiment of the present invention, the steam and gasifiedcomponents generated from said raw biomass material when it is heatedand pressure-formed are trapped within said barrel by means of saidpressure applying tool inserted into the barrel.

In another embodiment of the present invention, the barrel is acylindrical vessel, and said pressure applying piston is a cylindricalbody slidably fitted into the hollow of the cylindrical vessel.

Another embodiment of the present invention provides a method ofproducing solidified biomass comprising:

crushing raw biomass material which is photosynthetic product;

loading a barrel with said crushed raw biomass material;

inserting a pressure applying piston into a hollow of said barrel loadedwith said crushed raw biomass material;

pressure-forming said crushed raw biomass material by applying pressureto said material with said pressure applying piston while heating thematerial in a substantially sealed-up condition in the barrel;

maintaining the heating and pressurizing for predetermined time so as toobtain semi-carbonized solid and pre-semi-carbonized solid wherein thesemi-carbonized solid is produced by carbonizing the raw biomassmaterial without releasing combustible gas or liquid;

cooling said semi-carbonized solid mater or pre-semi-carbonized solidmatter while maintaining pressure of said pressure-forming to obtain acooled solid; and

taking out and drying said cooled solid,

wherein said pressure applying piston and the hollow of said barrel areformed such that the piston can be fitted slidably into the hollow withvery small clearance between their outer and inner peripheries.

In another embodiment of the present invention, the crushed raw biomassmaterial has a particle size of 3 mm or less.

In another embodiment of the present invention, the heating temperatureis 115-230° C., and pressure of pressure-forming is 8-25 MPa.

In another embodiment of the present invention, the metal particles areadded when loading said barrel with said crushed raw biomass material.

In another embodiment of the present invention, the particulate carbidehaving biomass as a main component is added to said barrel when loadingsaid barrel with said crushed raw biomass material.

In another embodiment of the present invention, the ash of materialhaving biomass as main component and being reduced to the ash is addedwhen loading said barrel with said crushed raw biomass material.

Another embodiment of the present invention provides method of producingcarbonized solidified biomass from solidified biomass of the invention,comprising: heating solidified biomass obtained from the above, allowingcarbonization of said solidified biomass by maintaining heatingtemperature and air pressure for predetermined time to obtain carbonizedsolidified biomass, cooling said carbonized solidified biomass whilemaintaining said pressure to obtain a cooled carbide solid, and takingout and drying said cooled carbide solid.

In the other embodiment of the present invention, the heatingtemperature is 250-350° C., and air pressure under which said solidifiedbiomass is heated is 8-16 MPa.

EFFECT OF INVENTION

The solidified biomass of the invention having maximum compressivestrength of 60-200 MPa and calorific value of 18-23 MJ/kg, can be usedin iron casting or iron making as alternative coke to be mixed with coalcoke. Further, as it has maximum compressive strength of 60-200 MPa, itcan be utilized as material for a variety of application purposes.

The solidified biomass having apparent specific gravity of 1.2-1.38 thatis not largely different from its true specific gravity of 1.4, haslittle internal void and carbon ratio per volume thereof is almostmaximized, so it is increased maximally in transportability.

The carbonized solidified biomass of the invention can be obtained byheating the solidified biomass of the invention in pressurized air for ashort time period. The resultant carbide, the carbonized solidifiedbiomass, has almost the same solid-combustion-characteristics asbincho-tan, the best vegetable charcoal in Japan.

The solidified biomass produced by using as material a mixture of rawbiomass material which is photosynthetic product and metal particles,can absorb heat efficiently due to the presence of the metal particlesin heating and pressure-forming process, resulting in homogeneousformation of pre-semi-carbonized or semi-carbonized solid matter.Furthermore, the metal particles added to the raw material andaccordingly contained in the bio-coke become molten metal in casting oriron-making process upon melting. Therefore, by adding particles ofmetals adjusted beforehand in mixing ratio of metals to the biomassmaterial, adjustment of ingredients in iron casting or iron making canbe achieved.

The solidified biomass produced by using as material a mixture of rawbiomass material which is photosynthetic product and a particulatecarbide having biomass as a main component, is increased in carbon ratioper unit weight and unit volume, therefore increased in calorific valueand combustion duration.

The solidified biomass produced by using as material a mixture of rawbiomass material which is photosynthetic product and ash of materialhaving biomass as main component and being reduced to the ash, can beutilized to adjust silicon content in the molten metal in iron castingor iron making without affecting heating performance of the furnace.

According to the methods of the present invention for producingsolidified biomass, heating and pressure-forming is performed bycharging a molding barrel with crushed raw biomass material and applyingpressure on the material by pressure applying piston inserted slidablyinto the hollow of the barrel with small clearance between the inner andouter periphery of the barrel and piston, so steam and gasifiedcomponents generated from the biomass material is trapped within thebarrel during the heating/pressure-forming process. Further the biomasscan be reformed with superheated steam. Therefore, pre-semi-carbonizedor semi-carbonized solid matter with high hardness and a high calorificvalue is obtained. The solidified biomass can be utilized as materialfor various application purposes for example for a pile or slope-plate.

By using crushed raw biomass material crushed into particles of 3 mm orsmaller in size as material for producing the solidified biomass, thematerial can be loaded in the barrel evenly.

By setting heating temperature to 115-230° C. and pressure ofpressure-forming to 8-25 MPa, pre-semi-carbonized or semi-carbonizedsolid matter having high hardness and calorific value can be formedwithout requiring excessive process energy.

By adding metal particles to the raw biomass material when charging thebarrel with the material, the mixture of the raw biomass material andthe metal particles can absorb heat efficiently, and homogeneouslyformed pre-semi-carbonized or semi-carbonized solid matter can beobtained. Furthermore, the metal particles added to the raw material andaccordingly contained in the bio-coke become molten metal in casting oriron-making process upon melting. Therefore, by adding particles ofmetals adjusted beforehand in mixing ratio of metals to the biomassmaterial, adjustment of ingredients in iron casting or iron making canbe achieved.

By adding a carbide having biomass as a main component to the rawbiomass material when charging the barrel with the material,pre-semi-carbonized or semi-carbonized solid matter increased incalorific value and combustion duration can be formed.

By adding ash of material having biomass as main component and beingreduced to the ash to the raw biomass material when charging the barrelwith the material, pre-semi-carbonized or semi-carbonized solid mattercan be formed with which silicon content in the molten metal in ironcasting or iron making can be adjusted without affecting heatingperformance of the furnace.

By heating the solidified biomass in an open atmosphere forpredetermined time and then cooling under the pressurized air,carbonized solidified biomass can be obtained in a short amount of time.

In this case, it is preferable to heat the solidified biomass totemperature of 250-350 under pressurized air of pressure of 8-16 MPa. Bythis, the solidified biomass is carbonized evenly and carbide with highdegree of adhesion can be obtained in a short amount of time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective external view of an example of the bio-cokeaccording to the present invention.

FIG. 2 is a flow chart showing production process of the bio-cokeaccording to the present invention.

FIG. 3 is a schematic sectional view of a cupola type melting furnacewhen the bio-coke of the invention is used as alternative coke.

FIG. 4 is a diagram showing temperature characteristic in a cupola typemelting furnace when the bio-coke of the invention is used asalternative coke.

FIG. 5 is a perspective external and partially broken view of a cupolatype melting furnace when the bio-coke of the invention is used asalternative coke.

BEST MODE FOR CARRYING OUT THE INVENTION

Solidified biomass of the invention (hereafter referred to as bio-coke)and processing methods thereof will now be detailed with reference tothe accompanying drawings. FIG. 1 is a perspective external view of anexample of the bio-coke(1) according to the present invention.Bio-coke(1) of the invention can be produced using all kinds of biomassmaterial that are photosynthetic products. As photosynthesized biomasscan be cited for example wood group, herb group, farm products, kitchenwaste, etc.

As wood group biomass can be cited for example wood, dead leaves,clipped or pruned branch and leaves, drift wood, waste paper, etc.

As herb group biomass can be cited for example stems of kenaf,sunflower, etc.

As biomass of farm products can be cited for example plantain stems,sesame stems, sweet-potato vines, rice hulls, etc.

As biomass from kitchen waste can be cited for example coffee grounds,tea grounds, bean-curd refuse, etc.

Such biomass is composed of cellulose, hemicellulose, and lignin as itsmain components.

As to heat-resisting properties of these main components of biomassunder atmospheric pressure, a large part of free water is dewatered byevaporation at about 100° C. Discoloration, decomposition or softening,gasification, and further generation of heat and progression ofcarbonizing occur at above the following temperatures for each of thecomponents; lignin (280˜550° C.), cellulose (240˜400° C.), andhemicellulose (180˜300° C.). Lignin is highest in heat-resistingproperty, followed by cellulose and hemicellulose in this order.

Cellulose is a highly crystallized chain polymer having distinct orderlybond-structure and polymerization grade of 2000˜15000, so it assumes animportant role in hardness property of the entire biomass.

Lignin has extremely complex three-dimensional bond-structure, so itscontribution to hardness property of the entire biomass is also high.

In contrast, hemicellulose has branched structure and polymerizationgrade of 50˜200 that is lower as compared with that of cellulose, so itscontribution to hardness property of the entire biomass is low.

We discovered that solid matter, i.e. bio-coke very high in hardness andsuperior in burning characteristic can be produced by allowinghemicellulose which is structurally brittle and low in heat-resistingproperty to be thermally decomposed thereby allowing development ofadhesion effect, compressing biomass material to allow thermosettingreaction to occur between cellulose and lignin while they aremaintaining their skeletons, and improving surface burningcharacteristic of solid.

Thermosetting reaction progresses due to arousal of reaction active sitebetween phenolic macromolecules contained in lignin, etc.

This is verified by the fact that presence of cresol in lignin moleculesof lignin-cresol reaction product was confirmed by H¹-NMR analysis. Thismeans that reaction occurred between lignin and cresol and cresol wasinfused into lignin molecules. This ensures that thermosetting reactionwill occur between phenol molecules and relatively homogeneous andstrong intermolecular network will be formed.

Further, it is possible to activate the thermosetting reaction byconfection of material and lower the temperature of pressure forming by10˜60° C. or further.

Therefore, it become possible to induce occurrence of thermosettingreaction at low temperature without carbonizing biomass and attainburning characteristic of solidified biomass substitutable for coalcoke.

FIG. 2 is a flow chart showing production process of the bio-cokeaccording to the present invention. Production method of bio-coke of theinvention will be detailed hereunder with reference to FIG. 2.

As shown in FIG. 2, process of producing the bio-coke is divided largelyin three steps.

In the first step, biomass material is broken into fractures of 3 mm orsmaller in size.

In the second step, the biomass material broken into fractures in thefirst step is heated to a temperature range of 115˜230° C. and moldedapplying pressure controlled in a pressure range of 8˜25 MPa.

In the third step, the state of heating and application of pressure inthe second step is maintained for 10˜20 minutes.

Then, the biomass is cooled while maintaining the application ofpressure in the third step, then the molded biomass is taken out anddried to complete production of bio-coke of the invention.

Production method mentioned above will be explained in a knowledgeableway.

Biomass material for producing the bio-coke is high in void fraction andits surface area is small in the state as it is, so it is unsuited toheating and pressure-forming. Therefore, in order to perform homogeneousmolding, first the biomass material is fractured to pieces of grain sizesmaller than 3 mm or smaller, preferably to 0.1 mm or smaller by acrushing means such as a mixer.

By this, the biomass material can be filled in a molding barrel(mentioned later) in a homogeneous state with increase density.Accordingly, contact area of the biomass pieces in heating andpressure-forming, and hardness of molded biomass increases.

Then, the crushed biomass material is filled in a molding barrel such asa cylinder, and after that a pressure piston for applying pressure isinserted into the molding barrel.

Here, the shape of the molding barrel and pressure piston is notparticularly specified, shape of cross section of them is preferable tobe circular. By adopting circular cross section, molding processing canbe performed stably even when the molding barrel or pressure piston istwisted slightly in pressure-forming process.

The inner diameter of the molding barrel and outer diameter of thepressure piston are determined to be nearly equal, and steam andgasified components generating from the biomass material when heatingand pressure-forming the biomass material can be retained inside themolding barrel, reforming of biomass by superheated steam is possible,and bio-coke having high calorific value and high hardness can beobtained.

After the fractured biomass material is filled in the molding barrel,heating and application of pressure is carried out under a condition oftemperature of 115˜230° C. and pressure of 8˜25 MPa as mentioned above.This heating and pressurizing process is maintained for 10˜20 minutes.As to heating method, it is suitable for example that a heating meanssuch as electric heating means is provided to surround the outercircumference of the molding barrel and the biomass material is heatedvia the molding barrel. Pressure forming is carried out by means of thepressure piston. As to method of applying pressure, it is suitable topush the pressure piston by means of a oil hydraulic jack, etc. However,attention should be paid, for there might occur the case that the vaporpressure generated in the molding barrel exceeds the pressure applied bythe pressure piston.

By carrying out heating and pressurizing under a condition mentionedabove, bio-coke can be obtained which is high in hardness and high incalorific value without requiring excess process energy.

This is because that, by performing heating under a temperaturecondition of 115˜230° C., hemicellulose is thermally decomposed,cellulose and lignin react with each other at low temperature under thepresence of superheated steam generated in the molding barrel whilemaintaining their skeletons, which acts synergistically together withpressure forming effect, thereby increasing hardness of the solidifiedbiomass.

It is more preferable that the heating and pressure forming is carriedout under temperature range of 185˜230° C. and pressure range of 12˜19MPa.

The bio-coke is cooled to 40˜50° C. or lower for about 30˜60 minuteswith the pressurized state maintained, then the bio-coke is taken out ofthe molding barrel. If the bio-coke is taken out when its temperature ishigher than said temperature range or when pressurized state is notmaintained during the cooling, adhesion effect of hemicellulosedecreases. As to cooling method, natural cooling by atmospheric air ispreferable. If cooling time is too short, occurrence of crack on thesurface and reduction in hardness may be induced.

Further, 5˜10 wt % of steam is condensed again in the bio-coke justafter it is taken out of the molding barrel because it has been moldedin near hermetical state, i.e. under near vacuum. Hardness can beincreased by dewatering through drying it.

Drying method is not particularly limited, and natural drying by leavingit in the atmosphere or drying in a temperature-controlled room of80˜100° C. can be cited for example.

The bio-coke produced through the process mentioned above is excellentin physical properties having specific gravity of 1.2-1.38, maximumcompressive strength of 60-200 MPa, calorific value of 18-23 MJ/kg, thatmeans superior both in hardness and combustion properties as comparedfor example with untreated wood biomass with apparent specific gravityof about 0.4-0.6, calorific value of about 17 MJ/kg and maximumcompressive strength of about 30 MPa.

The bio-coke of the invention is superior in hardness and combustionproperties also as compared with coal coke which has apparent specificgravity of about 1.85, maximum compressive strength of 15 MPa andcalorific value of 29 MJ/kg.

Apparent specific value of 1.2-1.38 of the bio-coke of the invention ismuch the same as that of true specific gravity of biomass. Like this,the bio-coke of the invention has few internal voids, so it is possibleto nearly maximize carbon ratio per volume and obtain nearly maximumheat energy generation of about 30 GJ/m³. Further, its transportabilityis increased maximally.

Next, variants of the production method of bio-coke according to theinvention will be described hereunder. In the following variants ofproduction method, production processing itself is not changed, onlymaterials to produce bio-coke are changed.

In a first variant, metal particles are added to biomass material andthe mixture is heated and pressure-formed.

As metal particles to be added can be cited for example Fe(iron),Ni(nickel), Cu(copper), Mn(manganese), etc.

As to grain size of metal particles, the smaller, the better. It ispreferable to mix metal particles of grain size of about 3 mm or smaller(more preferably 0.1 mm or smaller). This is to allow the metalparticles mixed evenly and brought into uniform contact with the biomassmaterial in the molding barrel.

The bio-coke produced in this manner will have maximum compressivestrength of 60-200 MPa, calorific value of 1-23 MJ/kg, and apparentspecific gravity of 1.3-6.0.

The bio-coke effectively absorbs heat applied from outside and contactreaction between pieces of biomass materials is promoted by the presenceof the metal particles, which leads to increased compressive strength ofthe moiled biomass.

The metal particles added to the raw material and accordingly containedin the bio-coke become molten metal in casting or iron-making processupon melting.

Generally, in casting or steel making process, adjustment of ingredientsis required in the final stage of processing in accordance withproperties required to the cast iron or steel (e.g. in steel converter,etc.). By adding particles of metals adjusted beforehand in mixing ratioof metals to the biomass material, the adjustment of ingredients in thefinal stage can be omitted, resulting in cost reduction.

In a second variant, carbides consisting of carbonized biomass, etc. areadded to biomass material and the mixture is heated and pressure-formed.

As bio-coke contains about 40-50 wt % of carbon in biochemical point ofview, it is inferior in characteristic of char combustion effected bysurface reaction of solid as compared with coal coke by about 50-60%.This does not affect the calorific value and heat-release temperature,however, relates to heat-release duration.

To deal with this, in this embodiment, bio-coke is formed by compoundingcarbide (calorific value of 33-42 MJ/kg) consisting of carbonizedbiomass, etc. with biomass material (compounded such that the carbide iswrapped around by the biomass material).

In this manner, bio-coke increased in carbon ratio by volume and byweight and improved in combustion duration and calorific value can beobtained. That means, surface combustion characteristic of solid can beincreased in this way.

The carbide consisting of carbonized biomass, etc. preferably be crushedto pieces of 3 mm or smaller in size, more preferably be crushed topowder of 0.1 mm or smaller in grain size.

Not only carbide made from biomass material but also carbide powder madefrom waste material derived from fossil resources can be suitably usedas the carbide mentioned above.

The bio-coke of carbide compounded type produced as mentioned above willhave maximum compressive strength of 60-200 MPa, calorific value of18-27 MJ/kg, apparent specific gravity of 1.3-1.4.

Therefore, when carbide powder is mixed to be 50 wt % of total materialfor example, the bio-coke produced in this manner will be increased incarbon ratio by about 75%, in calorific value by about 15% to 24.5MJ/kg, and also will be increased in combustion duration.

In a third variant, ash of biomass etc. are added to biomass materialand the mixture is heated and pressure-formed.

As material to obtain ash can be cited waste vegetable food,construction scrap uncoated with paint containing CCA (chrome, copper,arsenic), heat insulating materials, etc.

Generally, in casting and iron making, Fe—Si is cast in the furnacetogether with coal coke to add Si for component adjustment. Althoughbiomass material contains silicon, by adding ash of biomass, etc. tobiomass material and molding by heating and pressure-forming, siliconcontent in the bio-coke produced in the manner can be adjusted withoutdecreasing calorific value and hardness thereof.

In a fourth variant, biomass containing natural sulfur amply is added tobiomass material and the mixture is heated and pressure-formed.

Some kind of biomass contains sulfur, phosphorus, and the like in astate of lignin sulfonic acid or the like by 10% or more by volumeproduced in photosynthesis process. This is caused by the fact that alarge amount of sulfur and phosphorus, and the like are contained in thesoil in which such biomass grows.

As already mentioned, properties required to cast iron and steel differaccording to their intended purposes, so it is necessary to performcomponent adjustment in the final step of the processing. Sulfur,phosphorus, and the like also need to be adjusted.

Therefore, by adding biomass containing natural sulfur and the like by10% or more by volume to biomass material in a state similar in particlesize as that of the biomass material and molding by heating andpressure-forming, content of sulfur and the like in the bio-coke can beadjusted without decreasing calorific value and hardness, and content ofsulfur and the like in the cast iron and iron ingot can be adjusted incasting or iron making process. As natural sulfur, phosphorus, and thelike are compounded as additives instead of using those containedoriginally in fossil fuel, environmental load can be reduced.

When cast iron or iron ingot containing a large amount of sulfur or thelike is required, it is suitable to produce bio-coke using only biomassmaterial containing a large amount of sulfur and the like.

As described above, bio-coke according to the present invention is ableto be used as a heat source, reducing agent, etc. in a cupola or blastfurnace foundry or steel manufacturing. High compressive strength of thebio-coke allows it to be used as material for various applicationpurposes. The bio-coke of the present invention can be formed into solidof diameter of 0.1-250 mm and height of 1-1000 mm.

Here, as an example of use, a case used in a cupola as alternative cokewill be explained.

A schematic sectional view of a cupola type melting furnace(2) is shownin FIG. 3, its temperature characteristic in FIG. 4, and apartially-cutaway perspective view of the furnace in FIG. 5.

The cupola type melting furnace(2) shown in FIGS.3 and 5 is an elongatedclosed-bottom cylindrical furnace having an external surface coveredwith a steel plate(3) and having an internal surface formed with afirebrick wall(4). The tubular furnace(2) has a charging hole(5) on itsupper part, a tap hole(6) and a slug hole(7) near its bottom. Below thecharging hole(5) is disposed a charging platform(8). Slightly above thetap hole(6) is disposed a tuyere(11) continuously connected to a blastpipe(9) and wind box(10). On the furnace bottom(12) is disposed adoor(13).

When the cupola type melting furnace(2) is used for iron casting orsteel manufacturing, first, bed coke(14) is laid on the furnacebottom(14), and bare metal(15) and coke charge(16) are laid such thatthe bare metal(15) and coke charge(16) form alternate layers of baremetal(15) and coke charge(16) and empty space is formed between eachlayer.

Here, both the bed coke(14) and coke charge(16) are mixtures of coalcoke and bio-coke(1) of the invention with proportion of the bio-coke(1)of several % to 50%.

FIG. 4 a shows a temperature distribution within the furnace.

The distribution of the temperature within the furnace is as follows.

In the upper region(A) where the bare metal(15) and coke charge(16) arepiled, temperature gradually increases downward from about 500° C. toabout 1000° C. In the lower region (B) where the bed coke (14) is laid,temperature increases rapidly to about 1800° C., then decreases to about1600° C.

FIG. 4 b shows classification of conditions in the furnace. In the Leftpart of FIG. 4 b is shown classification according to the condition ofthe bare metal(15).

A preheating zone is formed in the upper part where the bare metal(15)and coke charge(16) are alternately piled. The bare metal (15) ispreheated in this region. A melting zone is formed in the border zonebetween the upper region (A) and the lower region (B). The bare metal(15) is melted in the melting zone. An overheating zone is formed in thelower part of the furnace where the bed coke (14) is laid andtemperature reaches a peak. The bare metal(15) melted in the meltingzone is overheated in the overheating zone. A liquid pool zone wheremolten metal(18) accumulates is formed in the bottom part below thetuyere (11). In the basin-region, a melted metal (18) is collected.

In the preheating zone, empty space is formed through which air orcombustion gas of coke flows. As the bio-coke (1) of the invention hascompressive strength about 10 times stronger than that of the coalcoke(17), the bio-coke(1) is not destroyed by the load applying fromupward and the empty space can be maintained.

In the right part of FIG. 4 b is shown classification according toreaction condition between the coke and gas in the furnace.

The melting zone and overheating zone are classified into a reductionzone and an oxidation zone as shown in the drawing, an upper zone beingthe reduction zone and lower zone being the oxidation zone.

In the reduction zone, CO₂ generated from combustion reaction in theoxidation zone is reduced. The reduction zone is formed by the reductionof the CO₂ and also gases resulting from gasification of thebio-coke(1), more specifically, by gases(CO, H₂, etc.) generated bythermal decomposition and gasification of the cellulose and lignin ofthe bio-coke (1). In other words, it means that the bio-coke (1) worksas a reducing agent.

When biomass is heated under a reduction atmosphere, the resultingexothermic reaction causes gasification, and further promotesself-gasification reaction. This is the reason why reduction zone(i.e.,the region in which the gasification of the bio-coke (1) occurs) isformed in the upper part of the bed coke (14) within the furnace.

The oxidation zone is the lower zone of the overheating zone, andtemperature reaches 600° C. or more in the oxidation zone. In theoxidation zone, bio-coke (1) is completely gasified or burned(oxidized)to ash and heat for melting the bare metal(15) is generated.

The reason why such an oxidation zone(i.e., the region in which thecomplete-gasification or combustion of the bio-coke (1) occurs) formedin the lower part below the bed coke (14) is that a combustion reactionis promoted by air blown in from the lower part of the furnace throughthe tuyere (11).

Now, the combustion properties of the bio-coke (1) will be set forth.

The coal coke (17) has a calorific value of about 29 MJ/kg. On the otherhand, the bio-coke (1) has a calorific value ranging from 18 to 23 MJ/kgwhich is slightly lower than the coal coke(17). Calorific value andheat-release temperature of the bio-coke change in accordance withchange in weight thereof caused by gasification/carbonization processesthereof.

First, at temperatures between ambient temperature and 250° C., thebio-coke is only heated, and an exothermic reaction does not occur.

At temperatures between 250° C. and about 600° C., heat is releasedwhile gas components such as CO, H₂, etc. being released due togasification of the biomass, however, temperature of heat release tendsto be slightly low.

At 600° C. or higher, char combustion of bio-coke is caused by surfacereaction of solid and heat release temperature comparable to that of thecoal coke (17) can be attained. The heat-release temperature of thebio-coke momentarily exceeds that of the coal coke (17) and calorificvalue of about 33-42 MJ/kg that is comparable to that obtained when coalis burned.

Therefore, full merit of the bio-coke (1) as a source of melting energycan be realized in an atmosphere of 600° C. or higher.

Iron casting process or steel manufacturing process using the cupolatype melting furnace (2) constructed as described above will be setforth hereinafter.

First, the bare metal(15) and coke charge(16) are introduced from thecharging hole(5) into the cupola type melting furnace(2) as shown inFIGS. 3 and 4, the coke charge(16) being a mixture of coal coke(17) andbio-coke(1) with the bio-coke(1) mixed in an appropriate proportion, forexample several % to 50% of the total amount of the mixture.

Next, when the inside of the furnace is heated while supplying air fromthe tuyere (11), the bed coke(14) in the reduction zone is gasified,volatile gases are generated to further enhance the formation of thereduction zone. The bed coke (14) in the oxidation zone is completelygasified or burned(oxidized).

The pile of the bare metal(15) and coke charge(16) alternately piled inthe upper part of the furnace collapses and moves down while beingpreheated as the bed coke in the lower region within the furnace isgasified or burned.

The bare metal moved down is melted by the heat generated by thecombustion of the coke laid in the oxidation zone, reduced by airsupplied from the tuyere (11), then taken out through the tap hole(6) asmolten metal(18).

The molten metal(18) can be obtained in a temperature state as hot asmolten metal obtained when conventional coal coke is used or evenhotter, owing to the superior combustion characteristics of the bio-coke(1) in the high temperature region as mentioned above.

As the bio-coke of the invention can be adjusted in components at theearly stage of its production, it is not needed to adjust in componentsusing converter. This makes it possible to simplify the entireproduction steps and thereby reduce cost.

As described above, the bio-coke according to the present invention canbe used as alternative coke to mix with coal coke by proportion ofseveral % to 50% in iron casting or steel manufacturing. In this case,effect similar or even superior to that obtained when 100% coal coke isused can be obtained.

As the bio-coke of the invention can be produced by using an apparatusof relatively simple construction, production cost thereof can bereduced as compared with coal coke.

Moreover, reduction of earth environment load can be attained by use ofthe alternative coke, the bio-coke of the invention.

Next, a usage example of the bio-coke according to the present inventionas material for various application purposes will be set forth.

There is a huge amount of easily-accessible biomass, and such biomass iscontinuously produced. Biomass with less utilization potential such asfood residues, weeds of riverbeds or the like is usually regarded asgarbage, because it is considered to have little value in its usage inmany cases. Such biomass is usually forced to be reclaimed orincinerated.

Considering that biomass is carbon fixed through photosynthesis and haswell-ordered organization structure, it is possible to construct acontinuous circulation of cascade structure, i.e. zero emissioncirculation environment by converting such biomass into material forvarious application purposes by taking advantage of its characteristics.

Bio-coke according to the present invention has maximum compressivestrength of 60-200 MPa that is higher than that of iron. In addition,the bio-coke can be made from food residues, weeds of riverbeds or thelike, its utility value as material is very high.

The bio-coke can be used as materials of pile-like products such asgarden fences, gardening piles and nails; plate-like products such aspanels for coaster or slope protection, bulkhead; etc.

When utilizing the bio-coke of the invention as a pile, some degree ofimpact resistance is required. To meet this requirement, it ispreferable that, for example, metal particles are added to raw biomassmaterial to improve reactivity between biomass components, or that rawbiomass material crushed roughly by taking advantage of fibroid naturethereof is added to improve continuity between the components.

As described above, according to the present invention, it is madepossible to utilize biomass disposed of utilized hitherto, and to showdirection in which articles made of plastic material derived fromchemical substances harmful to human bodies are replaced by articlesderived from biomass resources continuously recyclable.

Moreover, bio-coke used as material for various application purposes canbe used as a heat source as a matter of course. Therefore, when thearticles made of the bio-coke finished their roles and wasted, they canbe used again utilized as material of the bio-coke of the invention forexample by converting the used material into carbon dust and mixing withbiomass material for producing the bio-coke. Thus, cascade utilizingsystem, i.e. biomass cyclic use system is realized. Further, as thebio-coke decays naturally, it can be allowed to return to nature.

Next, a further example of usage of the bio-coke of the invention willbe set forth.

Carbide having high hardness can be manufactured in a short period oftime by further expanding the aforementioned method for producingbio-coke.

In this case, the bio-coke is further heated in an open atmosphere.Temperature and pressure are set to be 250-350° C. and 8-16 MParespectively to obtain about 10 to 30% yield in weight.

By this processing, nearly 100% carbide can be obtained in a shortperiod of time.

By setting temperature to 250-350° C. and pressure to 8-16 MPa, ahomogeneous carbide with high degree of adhesion can be obtained in ashort time.

In this processing, gasifying and exothermally reaction occur in thebio-coke and it decreases in weight as carbonization progresses, andwhen completely carbonized, solid matter is obtained as charcoal. Whenlive trees are carbonized under the same conditions as above, they arerapidly gasified due to pressurizing effects, and solid matter ascharcoal can not be obtained, instead only ash is obtained.

The carbide obtained by the processing mentioned above has calorificvalue of 30-35 MJ/kg and higher hardness than vegetable charcoal. Thesolid carbide matter has superior solid combustion characteristics andcan be used as a heat source comparable to bincho-tan, the bestvegetable charcoal in Japan.

EXAMPLES

Examples of bio-coke according to the present invention and productionmethod thereof will be detailed hereunder.

Example 1

Sawdust of Japanese cedar was crushed to pieces of size of about 0.1 mmby using a crusher of Matsushita Electric Works made.

The crushed material was charged to our own made molding barrel(acylindrical vessel of diameter of 40 mm and height of 250 mm) and thepressure piston was inserted into the barrel. The material was heatedand pressurized to a temperature of about 210° C. and a pressure ofabout 16 MPa for 10 minutes.

Thereafter, the material was allowed to cool for 60 minutes whilemaintaining the pressure. Then the bio-coke was taken out and dried inthe atmosphere.

The resultant bio-coke exhibited maximum compressive strength of about100 MPa and calorific value of about 21 MJ/kg.

Example 2

Bio-coke was formed by the same process as Example 1 except that heatingtemperature was set at 180° C.

The resultant bio-coke exhibited maximum compressive strength of about80 MPa and calorific value of about 20 MJ/kg.

Example 3

Bio-coke was formed by the same process as Example 1 except that heatingtemperature was set at 220° C.

The resultant bio-coke exhibited maximum compressive strength of about120 MPa and calorific value of about 23 MJ/kg.

Example 4

Bio-coke was formed by the same process as Example 1 except that amolding barrel of diameter of 20 mm was used and heating temperature wasset at 220° C. and pressure was set at 20 MPa.

The resultant bio-coke exhibited maximum compressive strength of about200 MPa and calorific value of about 23 MJ/kg.

Example 5

Bio-coke was formed by the same process as Example 1 except that bark ofJapanese cypress was used instead of Sawdust of Japanese cedar.

Bark of Japanese cypress was solidified more readily than Sawdust ofJapanese cedar. The resultant bio-coke exhibited calorific value ofabout 21 MJ/kg and maximum compressive strength of about 100 MPa.

Example 6

Bio-coke was formed by the same process as Example 1 except that amixture of 10% of sawdust of Japanese cedar and 90% of bark of Japanesecypress was used as material, and that the material was heated andpressurized to a temperature of about 115° C. and a pressure of about 21MPa for 15 minutes.

The resultant bio-coke exhibited calorific value of about 21 MJ/kg andmaximum compressive strength of about 83 MPa. Heating temperature wasable to be decreased by about 50° C. because of the presence ofhigh-phenolic macromolecules, polyphenol or the like, contained in thebark.

Comparative Example 1

The same process as Example 1 was adopted except that heatingtemperature was set at 240° C. In this comparative example, the materialwas entirely carbonized and not solidified.

As described above, it is recognized from above examples and comparativeexample that bio-coke superior in both in calorific value and maximumcompressive strength was obtained when heating temperature was 115-230°C. Whereas, when heating temperature exceeded 230° C., bio-coke was notobtained due to rapid proceed of carbonization and gasification.

Therefore, as carbonization and gasification proceed rapidly in a smallrange of temperatures between 230° C. and 240° C., the upper limit ofappropriate heating temperature for producing the bio-coke of theinvention was determined to be 230° C.

Further, an experiment for demonstrating substitutability of bio-cokefor coal coke was carried out by using bio-coke of maximum compressivestrength of about 100 MPa and calorific value of about 21 MJ/kg with anactual cupola of internal diameter of diameter of 300 mm (owned byNaniwa Roki Co., Ltd.).

Example 7

10% of the whole coke was substituted by the bio-coke of the inventionin an experimental operation of the cupola.

It was verified that metal drainage was possible similarly as the case100% coal coke was used without large difference.

The resultant cast iron exhibited tensile strength of 120-160 MPa in thesubsequent tensile test.

Example 8

Further, 50% of the whole coke was substituted by the bio-coke of theinvention. The result was similar to that of example 7.

Form these results, it was recognized that cupola operation can beperformed without difference from the case 100% coal coke is used evenif the bio-coke of the invention is substituted by 50% for the totalcoke.

Example 9

Bio-coke having maximum compressive strength of about 100 MPa andcalorific value of about 21 MJ/kg was further heated to 300° C. in aheating furnace under pressure of 8 MPa for 20 minutes.

The carbide obtained by this processing exhibited a yield in weight ofabout 20% and calorific value of about 34 MJ/kg. The carbide may becalled artificial bincho-tan, the best vegetable charcoal in Japan.

Example 10

Weeds collected on a riverbed were used as material to be formed into apile-shaped bio-coke. The pile-shaped bio-coke was molded by using apressure piston of which the material side end face was formed into aconical hollow. Molding were carried out under conditions the same asthat of example 1.

The resultant pile exhibited maximum compressive strength of about 80MPa.

INDUSTRIAL APPLICABILITY

According to the method of the invention, solidified biomass can beproduced with simple equipment with low cost, and the bio-coke producedby the method can be used as alternate fuel to coal coke as well asmaterial for a variety of application purposes.

1. A method of producing solidified biomass comprising: crushing rawbiomass material which is photosynthetic product; loading a barrel withsaid crushed raw biomass material; inserting a pressure applying toolslidably into a hollow of said barrel loaded with said crushed rawbiomass material so that pressure can be applied to said crushed rawbiomass material by said pressure applying tool; pressure-forming saidcrushed raw biomass materials by applying pressure to the material withsaid pressure applying tool slidably inserted into the barrel whileheating the material; allowing hemicellulose among main components ofsaid raw biomass material, i.e. lignin, cellulose and hemicellulose, tobe thermally decomposed and allowing low-temperature reaction to occurbetween cellulose and lignin while maintaining their skeletons, therebyobtaining semi-carbonized solid matter or pre-semi-carbonized solidmatter; cooling said semi-carbonized solid matter or pre-semi-carbonizedsolid matter while maintaining pressure of said pressure-forming toobtain a cooled solid; and taking out and drying said cooled solid.
 2. Amethod of producing solidified biomass according to claim 1, whereinsteam and gasified components generated from said raw biomass materialwhen it is heated and pressure-formed are trapped within said barrel bymeans of said pressure applying tool inserted into the barrel.
 3. Themethod of producing solidified biomass according to claim 1, whereinsaid barrel is a cylindrical vessel, and said pressure applying pistonis a cylindrical body slidably fitted into the hollow of the cylindricalvessel.
 4. A method of producing solidified biomass comprising: crushingraw biomass material which is photosynthetic product; loading a barrelwith said crushed raw biomass material; inserting a pressure applyingpiston into a hollow of said barrel loaded with said crushed raw biomassmaterial; pressure-forming said crushed raw biomass material by applyingpressure to said material with said pressure applying piston whileheating the material in a substantially sealed-up condition in thebarrel; allowing hemicellulose among main components of said raw biomassmaterial, i.e. lignin, cellulose and hemicellulose, to be thermallydecomposed and to allow low-temperature reaction to occur betweencellulose and lignin while maintaining their skeletons, therebyobtaining semi-carbonized solid matter or pre-semi-carbonized solidmatter; cooling said semi-carbonized solid matter or pre-semi-carbonizedsolid matter while maintaining pressure of said pressure-forming toobtain a cooled solid; and taking out and drying said cooled solid,wherein said pressure applying piston and the hollow of said barrel areformed so as to have very small clearance between their outer and innerperipheries.
 5. A method of producing solidified biomass according toclaim 1 or 4, wherein said crushed raw biomass material has a particlesize of 3 mm or less.
 6. A method of producing solidified biomassaccording to claim 1 or 4, wherein heating temperature is 115-230° C.,and pressure of pressure-forming is 8-25 MPa.
 7. A method of producingsolidified biomass according to claim 1 or 4, wherein metal particlesare added when loading said barrel with said crushed raw biomassmaterial.
 8. A method of producing solidified biomass according to claim1 or 4, wherein a carbide having biomass as a main component is added tosaid barrel when loading said barrel with said crushed raw biomassmaterial.
 9. A method of producing solidified biomass according to claim1 or 4, wherein ash of material having biomass as main component andbeing reduced to the ash is added when loading said barrel with saidcrushed raw biomass material.
 10. A method of producing carbonizedsolidified biomass from solidified biomass of the invention, comprising:heating solidified biomass obtained from the method of claim 1 or 4 inan open atmosphere, allowing carbonization of said solidified biomass bymaintaining heating temperature and air pressure for predetermined timeto obtain carbonized solidified biomass, cooling said carbonizedsolidified biomass while maintaining said pressure to obtain a cooledcarbide solid, and taking out and drying said cooled carbide solid. 11.A method of producing carbonized solidified biomass according to claim10, wherein heating temperature is 250-350° C., and air pressure underwhich said solidified biomass is heated is 8-16 MPa.